As one of the most promising pathways in the transition period towards the low carbon economy, a large scale implementation of electric vehicles (EV) is expected in the near future. Concentration of EV charging in a small area or within a short time will dramatically affect the load demand profile, especially the peak load in the distribution network. As a result, distribution transformers are facing hazards of shortened lifetime due to extra loads, and direct failures caused by potential overloads. Considering the large number of distribution transformers and the massive investment involved, the adaptability of the population of distribution transformers under future EV scenarios should be assessed. In this thesis, an assessment strategy for the future adaptability of distribution transformer population under EV scenarios is introduced. Assessing the adaptability is to understand the impact of the hot-spot temperature, loss-of-life, expected lifetime and failure probability of each individual in the distribution transformer population. Determination of hot-spot temperature of distribution transformers is essential for the assessment. In order to achieve accurate prediction of hot-spot temperatures under EV scenarios, thermal parameters should be refined for individual distribution transformers so that their thermal characteristics can be reflected more accurately than using the generic values recommended for all distribution transformers in the IEC loading guide. Two methods for the refinement are proposed in this thesis. One method is to curve-fit hot-spot temperatures measured in the extended heat run test; and the other is to calculate each parameter with developed equations in the loading guide with standard heat run test results. The assessment strategy is introduced and demonstrated on a group of selected distribution transformers from the population under three EV scenarios, i.e. Business as usual (BAU), High-range and Extreme-range scenarios, which represent 0%, 32% and 58.9% EV penetration levels respectively. Results show that EV charging would be less concerned on the acceleration of thermal ageing than the direct failure due to breakdown caused by decrease of dielectric strength in an event of bubbling. Since the peak load and hot-spot temperature under EV scenarios only last for a short time and would be compensated by low values during the rest time of a day, which eventually leads to a moderate thermal ageing. Occasionally, severe over-ageing can be caused by extremely high hot-spot temperatures, and the lifetime will be reduced to an unacceptable level. However, on such occasions, hot-spot temperatures would be high enough to trigger bubbling and reduce the dielectric strength of transformer's insulation system to a level that is incapable of undertaking the voltage stress, which eventually causes breakdown of transformers. In terms of the failure probability, results show that no distribution transformers are facing failure risks due to bubbling under BAU scenario. Failure starts under High-range scenario. If transformers possessing a failure probability over 50% are identified as high risk, then 13% of investigated transformers are at high risk under High-range scenario, while it increases to 39% under Extreme-range scenario. It is found that the failure probability is dominantly controlled by the peak load, other factors such as transformer age and installation conditions are less influential. A threshold peak load of around 1.5 p.u. is observed that distinguishes transformers in high risk from others under Extreme-range scenario. This observation could be applied to assist the asset management under future EV scenarios that the peak load of distribution transformers should be restricted below 1.5 p.u. to prevent potential failure due to bubbling.

Les structures en voûte sont présentes dans la plupart des anciens ouvrages maçonnés : tunnels, ponts, palais, cathédrales ou autres. Arches et voutes sont avec les murs les structures porteuses utilisées en maçonnerie. Leur bon état est alors la clef du bon fonctionnement d’un ouvrage. Les ouvrages maçonnés constituent à présent une proportion importante du patrimoine culturel. Toutefois, la plupart de ces ouvrages sont centenaires et le processus de dégradation s’est déjà enclenché depuis des décennies. Aujourd’hui, leur maintenance et réparation présentent des problèmes importants à leurs gestionnaires. Parfois des réparations ont été entreprises sans pour autant assurer la durabilité souhaitée. La fréquence des interventions se trouve augmentée et les coûts induits deviennent rapidement insupportables. Une situation qui a poussé certains gestionnaires à abandonner complètement leurs ouvrages, malgré leur valeur et leur importance patrimoniales. En effet, l’une des causes majeures d’abandon d’ouvrage est le coût excessif des inspections et des réparations. La question qui se pose dans de telles circonstances est de savoir comment mettre au point une stratégie à la fois efficace et surtout économique de maintenance de ces ouvrages, capable de prolonger leurs durées de vie ? Deux problèmes particuliers d’inspection sous incertitude sont traités : La présence localisée de perte de matière et la perte de matière généralisée. Pour traiter ces deux cas un programme a été développé. Le modèle, sur lequel il s’appuie, permet l’analyse globale de la voûte tout en minimisant au maximum le temps de calcul. Ce modèle constitue un compromis intéressant entre précision et temps de calcul. Les simulations de Monte Carlo ont été couplées à la méthode des éléments finis et implémentées dans un nouvel outil numérique, baptisé ArcProg_Z, afin de proposer une méthodologie cohérente pour l’évaluation probabiliste de la capacité portante des voûtes et de prévision de son mécanisme de ruine.Enfin, une étude de fiabilité de la voûte étudiée précédemment a été menée. La performance de la voûte a été évaluée à travers le calcul de sa probabilité de défaillance « instantanée et dépendante du temps » en fonction du coefficient de variation du module d’Young des différents segments. Les résultats obtenus pour chaque cas sont présentés et discutés. / The vault structures are present in most of the old masonry structures: tunnels, bridges, palaces, cathedrals or other civil infrastructures. Arches and vaults as well as walls are the supporting structures used in masonry. Their condition is then the key of the proper functioning of a structure. Masonry construction works are now a significant proportion of the cultural heritage. Most of them are century old and the degradation process is already running since several decades. Actually, the maintenance and repair continue to represent serious issues for their managers. Sometimes repairs have been undertaken without ensuring the aimed durability. The frequency of interventions is increased and the resulting costs are rapidly becoming unbearable. A situation has led some managers to completely abandon their buildings, despite their heritage value and national significance. Indeed, one of the major reasons for building abandonment is the excessive cost of inspections and repairs. The question that arises in such circumstances is how to develop a maintenance strategy that is both effective and most economical of these structures, capable to prolong their lifespan?Two particular inspection issues under uncertainty are discussed: The localized presence of material loss and generalized loss of material. To deal both cases, a program was developed. The model on which it is based, provides the overall analysis of the vault while minimizing the computation time. This model presents an interesting compromise between accuracy and computation time. Monte Carlo simulations are coupled with the finite element method and implemented in a software package named ArcProg_Z, in order to propose a consistent methodology for probabilistic assessment of the load bearing capacity of the vaults and predicting its failure mechanism.Finally, reliability study of the vault is carried out. The performance of the vault is assessed by calculating the probability of failure “instantaneous and time-dependent” according to the coefficient of variation of the Young's modulus of several segments.The obtained results for each case are presented and discussed.

Abstract Right heart failure may be caused by several etiologic factors such as pulmonary embolism, post coronary bypass, chronic obstructive pulmonary disease (COPD) and right heart infarction. Traditionally, treatment has consisted of fluid loading (volume expansion) and the use of inotropic agents. In the present series of studies, an experimental model of acute right heart failure was developed using right heart infarct. Treatment with drugs chosen to specifically improve right heart performance was then evaluated. The drugs used in this series were aminophlline, adenosine, nitric oxide (NO) and losartan. Aminophylline transiently improved cardiac index and pulmonary vascular resistance, but simultaneously caused an increase in heart rate and a decrease in stroke volume. Although it may reduce right heart afterload, aminophylline did not improve overall cardiac function in this experimental model of right heart infarction. Adenosine affected an increase in cardiac index during the adenosine infusion and in stroke index, while pulmonary vascular resistance and mean pulmonary pressure were decreased. There was a marked decrease in systemic vascular resistance as a result of the drug. Heart rate remained unchanged by the infusion. Discontinuation of the drug resulted in a rapid reversal of the hemodynamic changes. The continuous infusion of adenosine therefore appears to cause an effective arterial vasodilation, with a consequent unloading of right heart afterload. NO treatment significantly reduced right heart afterload. A significant deterioration was observed in cardiac output as well as in left and right ventricle stroke work indices. The use of NO in this model of right heart infarct affected a decrease in both right heart afterload and left heart preload, with an overall deterioration in global hemodynamics. Losartan was shown to decrease central venous pressure and wedge pressure, while cardiac output, left ventricle stroke work and stroke volume all showed improvement. Compared to the control animals, pulmonary vascular resistance, systemic vascular resistance and systemic pressures were unaffected by the drug, as was heart rate. An inhibition of angiotensin II action may therefore be of benefit in the treatment of right heart failure symptoms during the first hours after right heart infarct.

Magister Public Health - MPH / Introduction: Zambia is among the countries in the sub-Saharan African region most severely affected with HIV/AIDS. Approximately 1.2 million (14%) Zambians were living with HIV in 2010. Zambia introduced antiretroviral therapy (ART) in the public sector in 2002, starting with two pilot sites, and rolling it out throughout the country in 2004 and 2005. To date,approximately 350,000 people have accessed HIV treatment. The long-term success of ART programs depends on optimal adherence to ART by patients.In 2010 Livingstone General Hospital (LGH), the setting for the current research had over 7,000 enrolled for HIV care of whom 3,880 patients were on ART. By the end of June 2011, it was reported that 343 patients in this hospital were between 2 to 30 days late for their medication refill appointments. This meant that these patients had missed more than one dose, and thus not meeting the required 95% of medication for viral suppression. This study explored the barriers to medication adherence experienced by ART patients at Livingstone General Hospital (LGH). Methodology: An exploratory qualitative study was conducted. Six focus group discussions(FGD) were conducted with 42 patients on ART, and follow up semi-structured interviews with 7 patients identified during the FGDs. FGDs and semi-structured interviews were audio-tape recorded and transcribed verbatim. Thematic and content analysis of transcribed data was done. Results: The study found that the barriers to ART adherence included socio-economic factors such as poverty, use of traditional complementary and alternative medicines (TCAM) and religious beliefs. Patient related factors reported to negatively affect adherence were HIV related-stigma and discrimination, alcohol use, low literacy and education levels, busy daily schedules and forgetfulness. Regimen related factors included experiencing side effects to medication and complexity of treatment regimen. Negative staff attitudes, traveling long distances to health facility, long waiting times, lack of confidentiality, poor health information and poor patient-health provider relationships were the health system factors that negatively impacted on ART adherence. Conclusion: The combination and complexity of factors affecting adherence identified in this study have posed a challenge to adherence to ART. People have been forced to make adjustments to their routine lives in order to accommodate ART. The most problematic factor identified was the use of TCAM in combination with ART or as replacement of ART.

Background: Cardiac resynchronisation therapy (CRT) is a pacemaker-based therapy for patients with heart failure and dyssynchrony manifest as prolonged QRS duration. Approximately 30% fail to respond either symptomatically or echocardiographically. The role of several echocardiographic parameters to select patients and improve response rate has been studied. The utility of these parameters remains unclear. In particular recent advances in echocardiography with speckle tracking technology may provide more accurate assessment of dyssynchrony. This study aims to explore the role of echocardiography in prediction of CRT response and investigate mechanisms involved in response.Methods:Patients undergoing CRT according to national guidance were recruited. Baseline assessment included clinical examination, quality of life questionnaire, six minute walk test, electrocardiogram and detailed echocardiography. Follow-up assessment was performed six months after CRT. Response was defined as ≥15% reduction in left ventricular end-systolic volume. Baseline parameters of echocardiographic dyssynchrony were compared between responders and non-responders. Individual baseline and follow-up echocardiograms also were examined to assess mechanism of response.Results:51 patients were recruited and 40 patients completed six months follow-up. Echocardiographic response rate was 67.5%. Baseline parameters of dyssynchrony were not significantly different between responders and non-responders, and receiver operating characteristic (ROC) curve analysis suggested echocardiographic parameters have no role in prediction of response beyond QRS duration. Study of individual echocardiograms demonstrated several mechanisms of CRT response the relative importance of which vary between patients.Conclusion:Single echocardiographic dyssynchrony parameters appear to have no role in the prediction of CRT response. However, several mechanisms of response to CRT are identified, each of which may be identified echocardiographically, and echocardiography therefore continues to have an important role in pre-assessment of patients undergoing CRT.

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Heart failure is responsible for one in twenty deaths in the UK, and as the average age of the general population increases that number is predicted to rise over the coming years. Hypertrophic growth is believed to be an adaptive response to a chronic increase in workload under circumstances such as hypertension, yet it is also known to contribute to the pathological progression into heart failure. Abnormal calcium handling is known to play a critical role in determining disease progression, not only through its function as the driving force behind myocardial contraction and relaxation but also through directing the signals which regulate hypertrophic growth. Both isoforms 1 and 4 of the diastolic calcium extrusion pump plasma membrane calcium ATPase (PMCA) are present in the heart, yet unlike in other cell types their contribution to overall calcium clearance is only small; however their role in the disease process is yet to be defined. A novel mouse line was generated in which both PMCA1 and 4 were deleted from the myocardium (PMCA1:4dcko mice). Through comparison with PMCA1 knockout mice (PMCA1cko) this thesis set out to identify the specific function of each pump under normal conditions and during the development of pathological hypertrophy induced by pressure overload through transverse aortic constriction (TAC).Under basal conditions each isoform functioned independently, PMCA1 to extrude calcium during diastole and PMCA4 to regulate calcium levels during systole; however the loss of neither isoform impacted significantly on cardiac function. In response to TAC, PMCA1cko mice progressed rapidly into decompensation and displayed signs of systolic failure after just 2 weeks, whilst cardiac function was preserved in TAC controls. Calcium handling analysis revealed that prior to the onset of failure PMCA1cko mice displayed a distinct lack of adaptive changes to calcium cycling which were present in controls. In stark contrast, the additional loss of PMCA4 led to an attenuated hypertrophic response to TAC in PMCA1:4dcko mice which remarkably preserved cardiac function despite the absence of PMCA1. This adds to accumulating evidence which suggests that the inhibition of PMCA4 may be protective during the development of pathological hypertrophy, whilst highlighting the possibility for a novel role for PMCA1 in coordinating essential adaptations required to enhance calcium cycling in response to the increased demands imposed on the left ventricle during pressure overload.

M.Ed. / This research was undertaken because I, the practitioner researcher being the head of the Glenview Adult Education Centre in the Ekurhuleni West district – Gauteng, was concerned about the high failure and low pass rate of adult learners during the Senior Certificate examinations. This study aimed to explore in detail the main reasons for their failure and identify lessons that they offer for other adult learners. This study also focused on the reasons for the low levels of successes of the ABET (Adult Basic Education and Training) and how the centre can be viewed from a Freirean perspective. The ultimate aim of adult education is to produce citizens with critical thinking skills and it is with this breath that this study invites all stakeholders to work together to improve the current unacceptable failure rate of adults at the end of the Senior Certificate Examinations. Paulo Freire`s ideas are invoked as to provide possible solutions and not as a “quick fix” to the problem, to improve the current theoretical framework for thinking about results. His pedagogy is epoch making: he is a legend in his own time. Paulo Freire, educator, philosopher and political activator, has the capacity to excite and frustrate friends and critics alike. A genius like Freire (Taylor, 1993:73-74) was to bring together a range of pedagogies and learning teaching techniques to create a method of teaching which is known throughout the world as the “Mètodo Paulo Freire”, a method which is both a process of literacy acquisition and a process of conscientization, or conscientizacao (a word that he popularized and later dropped). It is based on the simple but fundamental technique of “problem posing” and there is therefore the antithesis of “Banking” Education, which seeks solutions or gives answers. It consists of daring to interrogate what is given, bringing into question known structures, and examining conventional or taken for granted explanations of reality. It discovers and then reacts to possible contradictions, identifying ways in which it can be said, done, or exists differently. However, despite, the urgent need for adult education to respond to the dictates of the needs of the community, development in education, effectiveness and quality at this Centre do not seem to be functioning as expected mainly because the learners are disengaged during the learning process. The stakeholders are further challenged to change their perceptions about adult education and its meaningful purpose to ensure a better life for adult learners. This route invites a healthy partnership whereby the concerns of the students and the community in line with the expectations of particularly the economy of South Africa as part of the global economy will form the backbone of such an understanding. Freires` pedagogy are used to reinforce my argument that better education should result in an improved contribution to economic growth, which in turn, should result in an improvement in the socio – economic growth of the previously oppressed adult learners. To obtain this objective at our Center, with very limited resources, it invites all stakeholders to unite to improve life for those who wish to obtain a Senior Certificate through part time studies. The study concludes with a few findings and recommendations, inter alia, that the adult learners are disengaged because of time constraints, different levels of prior learning, pressure of multiple responsibilities and a compact Senior Certificate programme. Recommendations are given that can possibly improve future practices and ultimately the success rate for adults in the Senior Certificate programme.

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